Oscar dos Santos Emboaba Júnior is sitting in the main reception at Chelsea's training ground, the rain hammering down outside and weariness from the overnight trek back from defeat in Bucharest dulling the mood. The Champions League holders are playing catch-up in a Europa League tie against Romanian opposition and travel to Manchester United, such distant league leaders, on Sunday in a daunting defence of the FA Cup they won last season. There is dissent in the stands, exasperation on the pitch, tumult all around. Cue a dose of perspective.

It should not need a 21-year-old Brazilian still adjusting to a new life on the other side of the world to offer clarity amid all the murky despair but, as one of the principal members of this club's new breed contemplates what is required to transform their fortunes, the word he repeats over and over again is tempo. The translation from the Portuguese is hardly required. Tempo is what every Chelsea manager craves, even the interims, but the one thing continually crushed beneath money-flushed expectations and ambitious demands. Time.

"It has been difficult this season because we have been in this period of 'transition'," says Oscar as he considers his first campaign in England. "We've lost some important games, been knocked out of competitions we'd hoped to win, and the Champions League was the biggest one. But we're a young team, a new team, with good players: Eden Hazard, David Luiz, Ryan Bertrand, Juan Mata …These are players who can help Chelsea become one of the greatest teams in Europe again.

"At the moment this is already a big club but, if we have three years playing together as a group, we will prove our quality. It's a question of time. The more games we play together, the more we mature.

"Grow up, develop. In time, you'll see that progress because we'll be winning competitions. People have to have patience and we need to have time. I have only been here eight months and am still early in the evolution process. Within one or two years, I'll have adapted to European football and that's my aim: to grow as a player. I'm already better than I was when I arrived. Hopefully I can continue my own development and show my own quality."

The transition from a team forged from weighty experience but reliant upon an ageing spine was always likely to prove traumatic, with Chelsea's penchant for regular makeovers in the dug-out whipping up that familiar feeling of chaos.

But, if there is long-term vision to be found, it has been in their more recent transfers. Hazard is 22, Mata 24, David Luiz 25. Oscar is the baby of that bunch, a player who arrived at Stamford Bridge last summer for £25m and as Brazil's emerging No10.

He has suffered the same inconsistency of form as this side over his debut season but Chelsea rightly believe they pulled off a coup by deflecting Tottenham Hotspur's interest in his signature. The flashes of quality he has served up have merely whetted the appetite. The most instantly memorable was that cushion, spin and whipped shot from distance that dumbfounded Leonardo Bonucci, Andrea Pirlo and Gianluigi Buffon, a trio of Azzurri left red-faced in the Champions League draw with Juventus in September when Chelsea still aspired to defend their European crown.

Last Saturday's display against West Bromwich Albion was arguably his most impressive in the Premier League, even if it lacked the goal it deserved. The periods on the periphery, either within contests or out of the team, have been more frustrating but the technique, vision and mouth-watering ability are obvious. This is a player who already boasts a hat-trick in a World Cup final, the Under-20s version against Portugal two years ago, and 13 caps for the full Brazil side.

His progress was never likely to be hampered by all the upheaval Chelsea might throw at him. The playmaker had endured two enforced breaks from the game, both born of a contractual dispute with his first club, São Paulo, whom he joined at 13. According to his agent, Giuliano Bertolucci, the salary originally promised his client was never forthcoming prompting Oscar to take São Paulo initially to court and then, in December 2009, to walk out altogether. In Brazil, a player can become a free agent if he is not paid for three months but it was June 2010, six months later, before the teenager joined Internacional.

Even then São Paulo disputed his right to move and it was not until early last year that their legal appeals came to a head, with the Brazil Sports Tribunal blocking Oscar featuring for Inter while his case was considered. He missed out on Copa Libertadores fixtures before a settlement for his 'sale' was finally reached on 30 May 2012.

"That whole period with the dispute over my ownership was a lot worse than anything that has happened this year because I couldn't play," he says. "I was helpless, I couldn't do anything. I just had to wait. It was a horrible time because the Olympic Games were approaching and I'd been playing very well before that, so to find out I wasn't allowed to take part was terrible. So frustrating. It wasn't something I really understood at first, but I had my family, my wife and my agent telling me to keep going. They kept motivating me and got me through it."

He has needed their support. Oscar lost his father, a fine amateur footballer turned furniture salesman in Americana, at the age of three – Oscar dos Santos Emboaba Sr was killed in a car accident – and has pursued his own professional career so vigorously "because of him". "He and my uncle [Alvaro Emboaba] played to a good level in Brazil but never had the opportunity to play professionally.

"They needed to earn money for their families instead, to work, so when I was offered the chance to have football as a career I pursued it for them. To represent my family."

His wife, Ludmila, is with him in London though their "family" has since been extended to include team-mates and compatriots. Ramires and David Luiz are near neighbours, the latter having apparently set himself the task of coaxing the shy Oscar from his shell. The centre-half, Brazil's captain and a potential future leader of this team, is something of a livewire, a larger-than-life figure who justifies his wild hairstyle. The youngster reveals, almost with a tinge of relief, that it is Mata who lives directly next door. "But it's helped having fellow Portuguese speakers around me, and we'll all socialise together. They're good guys, and they've gone out of their way to make me feel welcome. We're getting there. My understanding of English is improving, and my wife is taking lessons too." Next must come consistency in performance, rather than flurries of jaw-dropping form.

Oscar's best to date has been reserved for Europe – he disputes that has anything to do with a drop-off in tempo compared with the Premier League – where he has scored six times in nine appearances. Only three players, Cristiano Ronaldo, Edinson Cavani and Burak Yilmaz, boast more in Uefa competition this season, though his achievement is offset by having scored only against Brentford and Aston Villa, the last in an 8-0 rout, in domestic games.

Reward against United, the team who inflicted Chelsea's first Premier League defeat of this season in late October and effectively sparked the beginning of the end for Roberto Di Matteo, would be timely. "The goals will come, eventually," he adds. "In Europe I've had shots that have flown in whereas, in the Premier League, I'll have four or five and they'll find a way of staying out. It's just a matter of working hard and things will change. I'm still adapting my game and that goes back to the need for "time". It will come. For now, we have to believe the Manchester United game is an opportunity for us in a competition we want to win. We have to bounce back straight away after Bucharest, to listen to the coach's ideas and put them into practice.

"It's a hard game for us, but we have to make it one for them, too. I'm just learning with every match, and with every manager. I am progressing under Benítez, and I picked up a lot from Di Matteo too.

"The way to look at it is we're still competing for three things: the Europa League, the FA Cup and to qualify for the Champions League by finishing hopefully in the top three. Those are our objectives. We have things to achieve." In a squad craving positivity, the young Brazilian in their midst is on message.

Watch Brazil play Russia on Monday 25 March at Stamford Bridge. Tickets on sale at the stadium box office, tel 0871 984 1905 or chelseafc.com/tickets. Prices from £25 for adults and £12.50 for juniors/seniors